In general, the formation of a fine pattern in the manufacturing process of semiconductor devices is carried out using photolithography. In addition, multiple substrates referred to as transfer masks are normally used to form this fine pattern. In miniaturizing the pattern of a semiconductor device, it is necessary to use a short wavelength for the wavelength of the exposure light source used in photolithography in addition to miniaturizing the mask pattern formed on the transfer mask. In recent years, increasingly shorter wavelengths are being used as indicated by the transition from KrF excimer lasers (wavelength: 248 nm) to ArF excimer lasers (wavelength: 193 nm) for use as the exposure light source during the manufacturing of semiconductor devices.
Known types of transfer masks include conventional binary masks, provided with a light shielding pattern composed of a chromium-based material on a transparent substrate, and halftone phase-shift masks. Molybdenum silicide (MoSi)-based materials are widely used for the phase-shift film of halftone phase-shift masks. However, as disclosed in Patent Literature 1, MoSi-based films have recently been determined to exhibit low fastness to exposure light of an ArF excimer laser (so-called ArF light fastness). In Patent Literature 1, ArF light fastness is enhanced by carrying out plasma treatment, UV radiation treatment or heat treatment on an MoSi-based film following pattern formation, for forming a passive film on the surface of the MoSi-based film pattern.
Patent Literature 2 discloses a photo mask blank having a transition metal-silicon-based material film composed of a material containing a transition metal, silicon, oxygen and nitrogen. In this Patent Literature 2 as well, when exposure light of an ArF excimer laser (ArF exposure light) is radiated for a long period of time onto a transition metal-silicon-based material film having a pattern formed thereon, the technical problem arises in which a phenomenon occurs that causes a change in the pattern line width. On the other hand, Patent Literature 3 discloses a phase-shift mask provided with a phase-shift film composed of SiNx.